Carbon copy

[1] When copies of business letters were so produced, it was customary to use the acronym "CC" or "cc" before a colon and below the writer's signature to inform the principal recipient that carbon copies had been made and distributed to the parties listed after the colon.

[2] With the advent of word processors and e-mail, "cc" is used as a merely formal indication of the distribution of letters to secondary recipients.

While carbon paper was invented by Pellegrino Turri in 1801,[3] it was not widely used for copying until typewriters became common.

[5] The use of carbon copies declined with the advent of photocopying and electronic document creation and distribution (word processing).

It is still common for a business letter to include, at the end, a list of names preceded by the abbreviation "CC", indicating that the named persons are to receive copies of the letter, even though carbon paper is no longer used to make the copies.

An alternative etymology is that "c:" was used for copy and "cc:" indicates the plural, just as "p." means page and "pp."

A copy made with carbon paper
a typewritten carbon copy sheet of paper
As creating carbon copies requires relatively few resources, it became a common method for producing underground and clandestine newspapers, as seen in this French example from World War II.